Apparatus for operating vibratory conveyers or motors



June 9, 1942. H. H. HITTSON APPARATUS FOR OPERATING A VIBRATQRY CONVEYER OR MOTOR" Filed Oct. 22, 19:58

3 Sheets-Sheet l ATTX.

[/WE/y TOR r HARKER fihlTTsom,

June 9, 1942. HITTSQN 2,285,434

APPARATUS FOR OPERATING A VIBRATORY CONVEYER ORMOTOR Filed Oct. 22, 1938 3 Sheets-Sheet 2 a: E 5 m 2 m N 5 ggq-gjrm U 5 mm m n 'a 24% Elly. 2

HARKER H. HITTSoH H. H. HITTSON Filed 001;. 22, 1958 5 Sheets-Sheet 3 June 9, 1942.

APPARATUS FOR OPERATING A VIBRATORY CONVEYER OR MOTOR .0. Wm m 5.

Patented June 9, 1942 APPARATUS 2,285,434 ron ohm-rim; vmna'ronr CONVEYERS OB MOTORS Barker H. Hittson, Columbus, Ohio, assignor to The Jeffrey Manufacturing Company, a corporation of Ohio Application October 22, 1938, Serial No. 236,544

13 Claims.

This invention relates to a' system or apparatus for operating a vibratory conveyor or a vibratory motor.

'An object of the invention is to provide a. vibratory conveyor or a, vibratory motor having a natural period of vibration with'means to control the feeding of current impulses to said con-'- veyor or motor at a frequency to be determined by the natural period of vibration of the vibratory system of the conveyor or motor from any source of current, which may be either alternat ing current of' any frequency and number of phases, or direct current; by controlling the substantially constant. In many parts of the United States where power is supplied by large a public service power plants the frequency is substantially' constant, but in other parts of the United States and in many foreign countries the frequency of the power source varies appreciably,

. this being true in the United States particularly asymmetric flow of current as through an electron relay or tube, preferably of the vapor or gaseous electric discharge type, and to provide means to maintain substantially constant the amplitude of vibration thereof independent of .the load thereon, particularly by varying the Fig. 2 is a wiring diagram of the control system of my invention for the vibratory feeder or motor showing certain control elements diagrammatically;

Fig. 3 shows a modification of the circuit diagram of Fig. 2;

I Fi 4 shows another form of circuit diagram with a six phase out-put circuit; and

Fig. 5 shows a modification of the circuit of Fig. 4 employing direct current as the primary source of current supply.

Vibratory conveyors and vibratory motors for operating such conveyors, as well as vibratory motors designed for otheruses, such as for the operation of screens, barrel packers, coolers, driers, etc heretofore manufactured, includea class of equipment in which a vibratory mechanical system is provided having a natural period of.

vibration which is predetermined at a value near to but not equal to the frequency of the available electrical current. For example, it was quite common to provide a vibratory motoroperating any of the above mentioned types of apparatus which had a natural period of vibration of 58 cycles which is operated from 60 cycle current.

Certain definite limitations exist with such apparatus. In the first place, it is essential that where a small or. local power plant is the source of power. It is manifest that under conditions of variable in-put frequency the predetermined relation necessary for the proper operation of the vibratorymotors does not exist and as a consequence it has been impractical, if not entirely impossible, to supply these vibratory conveyors or motors where such conditions of variable frequency prevail.

There is another inherent objection to adjusting the natural period of vibration to or near to thefrequency of the power line. This adjustment requires an appreciable amount of time in 1 the process of manufacture because it is impos-- sible to calculate with absolute accuracy the natural period of vibration of any vibratory system, and while a close approximation can be realized from calculations a certain amount of trial and error is necessary in the building of the complete machine which consumes time and increases costs.

Still further, it is a fundamental fact that for the maximum efficiency and vibratory motor should vibrate substantially in exact resonance with the supplied current or, in other words, at its natural period of vibration, but it has been found in the commercial machines above mentioned that this has an undesirable result in that the amplitude of vibration of the motor varies appreciably'with the load on the material supporting surface or deck. As a result it has been the frequency of the source of electric supply be 5 inadvisable to tune the vibratory mechanical syster in exact resonance with the current supplied because the amplitude of vibration may become excessive and injure the machine under no-load conditions if the current supplied is 'suflicient under full-load conditions to do the work efllciently and effectively.

All of the above mentioned deficiencies have been overcome in the apparatus and method of my invention. That is, the vibratory conveyor of vibration, therefore, resulting in maximum .efliciency. An exact predetermination of the natural period of vibration is also unnecessary.

Still furthea-this makes possible any desired frequency of operation quite independent of the frequency of the in-put current (and by the use of the term "frequency of in-put current or the I equivalent, it .is to be understood that applicant ,a substantially constant amplitude of vibration of the conveyor or motor, which amplitude may I be variably adjusted.

Referring to Fig. 1 of the drawings, there is disclosed a vibratory conveyor, the general structure of which is disclosed in more complete detail in the application of Earle V. Francis, Serial No. 221,868, filed July 28, 1938, now Patent No. 2,161,342, dated June 6, 1939, entitled Vibratory feeder, to which reference is made for a more complete disclosure thereof except for specific differences herein pointed out. Said vibratory conveyor may be briefly described as comprising an electro-magnetic motor i0 formed by a main frame ii to which is attached a plurality of spring bars !2 the ends of which are clamped in said main frame II and the centers of which are clamped to an armature shaft [3 to which is attached a vibratory armature it.

Mounted on the main frame Ii is a bracket means IE to which is adjustably attached a field structure 86 including a field winding H. The armature shaft i3 is provided with front and rear brackets 93 upon which is supported a deck l9 adapted to receive material at its upper end, for example from a feed hopper, and discharge it over its lower end. While the deck I9 is shown sloping downwardly this is not at all essential for it may be horizontal or it may even be in clinedupwardly to a slight extent. I

The motor H3 is supported from a base 20 by a plurality of rubber cushion'members 2|. To aid in supporting the armature shaft 13, particularly to prevent distortion of the spring bars it by twisting, the base 2d carries a forward extending bracket 22 which supports an' adjustable cup 23 carrying a rubber cushion 2d upon which the armature shaft it rests adjacent its forward portion.

Mounted upon the main frame I! is a switch mechanism 25 which comprises a base 26 rigidly attached to said main frame Ii within which is mounteda shaft 21 (see Fig. ,2), keyed to a worm 253 which meshes with a sliding bar 29 having teeth 3ilthereon which mesh with the teeth of the worm 28. The bar 23 is preferably made of insulating material and carries a plurality of integral or attached upstanding bosses including an end boss 3i and three forward bosses 32. The base 25 provides appropriate lateral bearing surfaces along the sides thereof for the sliding bar 29 to support it for free sliding movement. Adjacent one side edge of the bar 29 and the top of the base 26 is a micrometer type scale 33 (see Fig. 1) by which the position of the slide bar 28 may be determined to give a direct reading of theamplitude of vibration of the armature shaft 13 and deck 19.

' To provide for rotation of the worm 28 the shaft 21 is provided with a knurled handle 34. There is preferably sufiicient friction on the shaft 21 and/or on the worm 28 to hold it in any position to which it is adjusted, inspite of the vibration of the motor. If desired, clamping means may be added to clamp the sliding bar 29 releasably in any .position ofadjustment.

Extending upwardly from the rear ends of bosses 32 are fiat flexible spring plates 35, 36 and 31, such as bronze springs, each carrying a forwardly extending switch contact which, for example, may be made of tungsten. Also extending upwardly from the forward end of boss 3| is a similar spring plate 38 which carries a rearwardly extending switch contact. The upper ends of the spring plates 35, 36, 37 and 38 are attached to a striking plate 39 preferably made of insulating material which is adapted to be nositioned adjacent to or in contact with the deck or armature of the conveyor or the vibratory motor armature.

Extending upwardly from the forward ends of the bosses 32 is a plurality of spring plates 40, 4|

switch or circuit maker and breakerll. Asso-' ciated with the spring plate 46 is means for adjusting the air gap between the contacts of switch d! which may take the form of a knurled screw 48 threaded through a boss on the spring plate t6 and abutting an upstanding abutment on the boss 3!, as illustrated in Fig. 2 of the drawings.

Referring particularly to Fig. 2 of the drawings, there is seen a source of electric current which, in this illustration, comprises three phase alternating current of any desired frequency which is delivered over the three power line conductors 5d, at and 52. Associated with the source of current are three electron relays or electric valves which are preferably of the vapor or gaseous electric discharge type comprising relays or valves 53, 5d and 55. The valves illustrated are of the three electrode type each including an indirectly heated cathode, a grid and an anode.

' The anodes ofthe three valves 53, 54 and 55 are ,ondary windings associated with the transformer 58. It is, of course, evident that any other appropriate means may be employed for heating the filaments associated with said cathodes, such as a separate transformer with three secondaries.

To control the flow of current from the conductors 53, 5! and 52 to the field winding I] through the valves or relays 53, H and 55 in accordance with the natural period of vibration of the conveyor or vibratory motor each of said.

valves or relays 58, 54 and 55 is provided with a control or grid circuit including a grid resistor, grid biasing battery and excitation transformer. Those parts for the valve 53 comprise the grid resistor 58, biasing battery 50. and excitation transformer 5|. I

As illustrated in the drawings, the valves or relays 53, 54 and 55 are preferably of the type that, in the absence of a negative bias on the grid they are conducting, it being understood, of course, that unless the excitation transformers, such as transformer 6| are excited, the biasing batteries, such as the battery 58, maintain a negative bias on the grids to render all of said valves or relays 55, 54 and 55 nonconducting. If desired, these valves or relays 58, 54 and 55 may be of the type which are normally non-conducting when there is no bias on the grid and are rendered conducting only when a positive bias is placed upon the grid. In case said valves or relays are of this type, the biasing batteries, such as the battery 6|, may be eliminated.

In addition to the grid control circuit for the valve or relay 53, as above described, including the excitation transformer 5|, it is, of course, evident by reference to Fig. 2 that a similar and independent grid control circuit is provided for each of the relays or valves 54 and 55 and the grid control circuit for relay or valve 54 includes an excitation transformer 52 while the grid control circuit for relay or valve 55 includes an excitation transformer 53.

To provide for the excitation of the grids of the valves or relaysa53, 54 and 55 to render them conducting and non-conducting in accordance with the natural period of vibration of the vibratory conveyor or motor, and also to control the amount of current delivered to the field winding so as to maintain the amplitude of vibration of the deck or armature of the vibratory motor or conveyor substantially constant at'a predetermined value I provide controllable energizing circuit means for the excitation transformers 5|, 52 and 53, now to be described.

Associated with the conductors 58,, 5| and 52 is a phase shifting mechanism 54 which is generally of a construction well understood in the electrical art and may be briefly described as comprising a stator winding 55 connected at equi-distant points to the three conductors 58, 5| and 52 to provide a rotating magnetic flux within the phase shifting mechanism. The phase shifting mechanism additionally includes an adjustable rotor 65 carrying three independent phase windings 51, 58 and 59.

The phase relation of the voltages induced in the windings 51, 58 and 58 with respect to the voltages on the conductors 58, 5| and 52 will, of course, depend upon the position of the rotor 55 and to control this phase relation a phase adjusting mechanism I is provided. The phase ada damping piston 15 adapted to slide in an elon-' .gated cylinder 11 and make a relatively close contact therewith which tends to cause slow movement of the piston I in the cylinder 11 under "he influence of the solenoid 15 or of a spring 18 which tends to push the cylinder 15 toward the left, as viewed in Fig. 2 of the drawings.

The cylinder I1 is preferably made of insulating material. The right hand end of the cylinder 11 is provided with a removable cap 18 which is preferably threaded thereto to provide for the insertion and removal of the spring 18. In practice, preferably a plurality of springs 18 are provided to adjust the speed of movement of the piston 15 under the influence of said spring. If desired, extensive threads may be provided on the cap 19 and the cylinder Tl as another means of adjusting the efiective rate of movement of the piston I5 under the influence of said spring 18.

To provide a source of power for the solenoid 15 I provide a full-wave rectifier tube 80, the two plates of which may be energized from any desired source. In Fig. 2 of the drawings the plates are connected across the terminals of one of, the windings of the transformer 58 by conductors 8| and 82, and the cathode is connected to the center tap thereof in series with the solenoid 15 by way of conductors 83, 84 and 85.

If desired, and particularly in the interest of maintaining a balance on the transformer 58, a separate energizing transformer may be supplied for the rectifier tube 80 which may be connected across any of the two lines 58, 5| and 52. Also, in Fig. 2 of the drawings, an obvious heater circuit is provided for the heating element of the cathode of said tube 88. The tube 88 is maintained in a normally non-conducting condition by virtue of a negative bias being placed on the two grids thereof from bias battery 85 which is connected between the cathode and the two grids of said tube 88 through grid resistor 81.

As hereinafter described in more complete detail, when the contacts of switch 4! are closed, the bias battery 85 will be shunted through grid resistor 81 over conductor 83 and conductor 38 thereby removing the negative bias from the grids of the tube 80. Said tube is preferably of the vapor electron discharge type which is normally conducting inthe absence of a megaveyor is in a non-operating condition and it is desired to start it into operation the parts will be, substantially in the positions illustrated in Figs. 1 and 2 of the drawings. Upon the closure of the main line switch (not shown), to the conductors 50, 5| and 52, three phase alternating current will be delivered to said conductors 50, 5| and 52, and alternating current voltages will be transferred to the relays or valves 53, 54 and 55 by way of said conductors 50, 5| and 52, and by way of tlieconductor 51 associated with the center tap of the transformer 58 and field winding ll of the vibratory conveyor.

Each of the relays or valves 53, 54 and 55 is, however, provided with a normal negative bias on the grid thereof provided by the grid circuit above described, including the battery and grid resistor such as battery 58 and grid resistor 58 associated with the relay or valve 53. It is manifest, however, that if an alternating current of the proper voltage is supplied to the secondof course, tend to overcome the negative grid bias on said tubes 53, 54 and 55 during half of the cycle thereof, and to increase the negative grid bias during the other half of the cycle. If these voltages are in phase with the cathode anode voltages it is evident that a maximum amount of current will fiow through each valve or relay 53, 54 and 55 during each half cycle that the cathode-anode voltage is of the proper polarity. v

It is further evident that if this phase relation between the cathode-anode voltage and the .grid voltage'is adjusted so that they become out pressed grid voltage on the relays or valves 53, 54 and 55 is such as to produce a maximum current flow through said relays or valves and to said field winding l'l. Therefore, when the main switch is thrown, as above set forth, a maximum amount of current will flow through the relays or valves 53, 54 and 55 to the field winding l1 of the vibratory conveyor. This energization of of phase a progressively increasing amount, the

amount of current which flows through each valve or relay 53, 54 or 55during each period of conductivity thereof will be progressively decreased and it may be stated that the apparatus is so adjusted that the phase shifting mechanism 64 controls this phase relation automatically to maintain the amplitude of vibration of the conveyor substantially constant.

The circuits which energize the transformers BI, 52 and 53 from the windings 61, 68 and 53 respectively, are easily traced by reference to Fig. 2 of the drawings, but in the interest of completeness that for transformer 5| will be completely traced. Startingfrom one side of the winding 6] the circuit leads by way of conductor 88 to one terminal of the primary of the transformer 5|, the other terminal of which leads by way of a short conductor to spring plate 42 which being of conducting material leads to the contacts of normally closed switch 45 from which the circuit extends by way of spring plate 31 of conthe field winding I'l will attract the armature [4 of said vibratory conveyor and pull the armature shaft l3 and deck l9 rearwardly which will be effective to open the contacts of the switches 43, 44 and- 45, This opening of said contacts 43, 44 and 45 will de-energize the .transformers 5|, 52 and 63 under which conditions the normal negative grid bias will be applied to-the grids. of said relays or valves 53, 54 and 55 and render them all non-conducting, thereby shutting oil the current flow to the field winding l1. course, will allow the armature l4, armatureshaft I3 and deck l9 to move to the right, as viewed in Fig. 1 of the drawings, under the influence of the energy stored up in the spring bars l2. This movement of the deck l9 and armature shaft l3 to the right will cause switches 43; 44 and 45 to close again which will result in the energizeducting material to conductor 90 which leads to the other terminal of the winding 51. It is thus evident that an alternating current voltage of adjustable phase is supplied to the grid transformer 6| and is under the control of the con- 5 tacts of switch 45. As previously indicated, by adjusting the position of the rotor 55, by the phase shifting mechanism 54, as hereinafter described in complete detail, the effective impedance of the relays or valves 53, 54 and may be adjusted'and the period of conductivity and thus the amount of current which fiows through it during each cycle may be adjusted.

It is also to be noted that the primary terminals of th transformer 5| have a resistor 9| connected across them which provides a voltage drop which is impressed upon said transformer primaries.

It may be stated that the transformer 62 is connected in a manner quite similar to the connections to transformer 6| to the phase winding 38 and is controlled by the contacts of switch 44. Likewise, transformer 53 is energized from phase winding 55 and is controlled by contacts of switch 43.

It may be stated that the spring 18 of the phase adjusting mechanism 10 when in its extreme position of afiustment, that is, with the piston 16 and plunger 13 moved to their extreme lefthand position, the phase relation of the imtion of transformers GI, 62 and 53 to allow an-' other impulse of current to flow through the relays or valves 53, 54 and 55 to the winding 11 under which conditions the above described action will be repeated.

It isthus evident that the vibratory conveyor i will be set into vibratory motion which will continue so long as the main line switch is closed.

It is, of course, evident that due to the three phase relation of the voltages applied to relay or valves 53, 54 and 55 these valves will not conduct current simultaneously but will conduct current in sequence. Due to the overlapping of the half cycles of the three phases, one of said relays or valves53, 54 and 55 will substantially always be conducting and thus there will. always be current available for the field winding H from one of said relays or valves 53,54 and 55. This current supply to the 'field winding I! will, of course, be pulsating direct current and the impedance of the winding I! will tend to smooth out the ripples therein. Should said winding l1 not be sumcient as a filter to smooth out the ripples any additional filter of well-known construction may be added.

Furthermore, if desired, instead of a three phase out-put, a six phase out-put may be employed, using six tubes, the grids of which are independently controlled through a phase shifting mechanism which has six windings instead of three. Such a system is disclosed in Fig. 4'

The amplitude of vibration of the vibratory conveyor or motor is adjusted in a rough manner merely by adjusting the switch mechanism 25;

that is, by operating the handle 34, the striking plate 39 may be moved towards and from the normal position of the deck I! or armature shaft l3 which strikes it. It is, of course, evident that by moving the striking plate 39 close to the deck IS the switches 43, 44 and 45 will be opened on a relatively short stroke of the armature or deck which, in itself, will tend to control the amplitude of vibration by cutting short the time of the current flow to the field winding l1. However, to make for a more accurate adjustment which will maintain the amplitude of vibration substantially constant at any adjustable value the phase shifting mechanism 64 is operated from the phase adjusting mechanism by way of switch 41 in a manner now to be described,

As was previously set forth, the-spring 18 tends to move the plunger 13 to the left, as viewed in Fig. 2, which tends to bring the phase relation of .the grid potential on the relays or valves 53, 54 and 55 in phase with the anode-cathode potential which tends to produce a maximum current flow through said relays or valves 53, 54 and 55. Therefore, the spring 18 continuously tends to increase the amplitude of vibration of the deck or armature of the conveyor or motor by tending to increase the current flow thereto. The contacts of switch 41 if closed periodically during each backward portion of the stroke of the deck or armature of the vibratory conveyor or motor, closes a circuit which controls the flow of current to solenoid which, when energized, tends to move the plunger 13 to the right, as viewed in Fig. 2 of the drawings which, in turn, tends to shift the phase shifting mechanism 64 to decrease the current flow through the tube 53, 54 and 55. This control is effected as follows.

The solenoid 15 is connected in the cathodeanode circuit of the full-wave rectifier 80. The circuit may be traced from the cathode thereof by way of conductor 83, conductor 84, solenoid 15 and conductor 85 to the center tap of the transformer, the outer terminals of which are connected to the opposite plates of the full-wave rectifier 80 by way of conductors 8| and 82. Unless the contacts of switch 41 are closed no current will flow in solenoid 15 because of the negative bias on the grids of the tube 80 effected by battery 86, as above set forth. However, should the amplitude of the vibration of the deck I! or armature I3 of the conveyor or motor be sufficient to close the contacts of switch 41, the negative bias on tube 80 will be temporarily removed, as above described, and an impulse of current will flow to the solenoid 15 and move the moving parts of phase adjusting mechanism 10 to the right, which will adjust the phase shifting mechanism 64 to decrease the current flow through relays or valves 53, 54 and 55.

It is thus evident that spring 18 continuously acts in a manner which tends to increase the amplitude of vibration of the conveyor or motor which, unless counteracted, would cause the closure of the contacts of switch 41 during each stroke of the vibratory conveyor or motor. However, whensaid contacts of switch 41 are closed, due to the increased amplitude of vibration, the phase adjusting mechanism 10 will. operate through plunger 15 to control phase shifting mechanism 64 to reduce the amplitude of vibration of the deck I9 and armature shaft l3. As a consequence, the mechanism will operate automatically so that phase adjusting mechanism 10 floats back and forth to maintain the amplitude of vibration of the conveyor or motor so that contacts of switch 41 are just slightly closed during each vibratory movement of the deck l9 or armature shaft l3.

To provide for the independent adjustment of the switch 41 superposed on the adjustment of this switch in combination with switches 43, 44 and 45, the screw mechanism 48, above described, is provided. It is thus evident that by setting the switch mechanism 25 to any predetermined position, as determined by the scale 33, the amplitude of vibration of the vibratory conveyor or motor may be maintained substantially constant.

Furthermore, it is a matter of considerable importance, as previously indicated, that the vibratory conveyor or motor operates at its own natural period of vibration and directly controls the frequency of the impulses fed toit thereby insuring that said impulses will have the same frequency as its natural period of vibration, Furthermore, this control is effected without requiring the interruption of any power circuits by virtue of the fact that it is controlled by controlling the current flowithrough electron relays or valves by controlling the grid bias of said valves, it being well known that the currents which flow in the grid circuits of such tubes are extremely small under any conditions.

It is, of course, evident, that the natural period of vibration of the vibratory conveyor or motor is determined by the weight of the mass to be vibrated and the restoring force of the spring bars l2. That is, the spring bars l2 in cooperation with the mass to be vibrated comprising the armature shaft l3, armature I4 and deck I9 and any parts which are rigidly attached thereto, forms a vibratory system having a natural period of vibration and this natural period of vibration will vary with the number and size of the spring bars I! and with the weight of the parts supported thereby.

As was above set forth, in previous machines of this general type, it has been a somewhat protracted operation to select the exact number and size of bars I 2 to predetermine the natural period of vibration of the vibratory system to a definite relation to the frequency of the available current. vIn the apparatus and method of my invention thi is entirely eliminated because any number of bars 12 may be supplied which approximately approaches the desired frequency of vibration of the system which can be calculated within a fairly close degree of accuracy,

such as within ten percent, and no further determination is necessary because the impulses supplied to the vibratory conveyor or motor are controlled directly by and in exact synchronism with said natural period of vibration.

As was further setforth, this eliminates entirely the problem encountered where the fre quency of the available source is not constant.- Still further, this makes for a mechanism of the highest efiiciency because it is well known that when a vibratory conveyor or motor operates at its natural period of vibration maximum efiiciency' is realized. The automatic control' of the amplitude of vibration makes this operation at the natural period of vibration quite practical though it is to be understod that the system and for controlling the amplitude of vibration and maintaining it constant may be employed with a conveyor or motor of the vibratory type known in the prior art in which the conveyor or motor does not control the frequency of the impulses supplied to it. In such a case, insteadof employing the phase adjusting mechanism 10 to control phase shifting mechanism 64, the mechanism I0 will be employed to control a rheostat in series with the field winding II. In short, in the complete system and method it is preferred that both the constant amplitude maintaining mechanism and the frequency controlling mechanism which controls the frequency of the impulses supplied to the motor by the natural period of vibration of the motor itself be employed; but either of said mechanisms may be independently employed.

In Fig. 3 of the drawings, there is illustrated a partial circuit which is to be understood as a modification of the circuit of Fig. 2 in which'the bias on the grids of tube 80 is normally negative but which will be removed entirely under conditions of substantial equality between the amplitude of vibration and the desired amplitude of vibration, while under conditions of extreme vibration as compared to the desired amplitude of vibration a positive bias will be placed upon the grids of the tubes to increase to a maximum the conductivity thereof. The tube 80 employed in this circuit preferably has a characteristic that when there is no bias on the grids an average amount of current. will flow, when there is a positive bias a greater amount of current will fiow, and when there is a negative bias no current will flow. In this modification of the circuit the sliding bar .29 is provided not only with the adjustable switch 41 but with an additional switch 41' which is normally closed and includes one contact carried by the spring plate 38 and another contact carried by an adjustable spring the amplitude of vibration of the conveyor or contacts ofxswitch 41 are closed to remedy the situation in a very short time.

Attention is now directed to Fig. 4 of the drawings and to another embodiment of my invention. In the embodiment of the invention of said Fig. 4, main line conductors I00, IN and I02 terminate in a delta-connected primary of a transformer I03, the secondary of which is connected in six phase star in a well known manner.

The outer terminal of each of the six phases of V the transformer I03 leads to an electron discharge relay or valve preferably of the gaseous or vapor type, the six valves being seen at I04,

three electrode type and the plate, or anode of each valve I04 to I09, inclusive, is connected to an outer terminal of anindividual winding of the secondary of the transformer I 03. The

cathodes of all of the valves I04 to I09, inclusive,

are connected in parallel to a conductor I I0.

In the interest of simplification the heating I circuits for the cathodes of the valves I04 to I09, inclusive, are notshown but it is obvious that they may all be heated from a single heating transformer which may be connected across any two of the power lines I00, I0l, I02, or in any other desired-manner. One terminal of the field winding I1 is connected by way of conductor III to the center tap of the secondary of transformer 1 I03. The other terminal of said field winding I] is connected to the cathodes of the valves or relays I04I09, inclusive, which, as above set forth, are all connected in parallel.

tube 90 and is connected to an intermediate point of the battery 93. It is evident that ander these conditions negative bias is placed on the grids of the tube 80. The spring plate 46 in this modification of the circuit is connected to the positive terminal of the battery 93 by conductor 95.

During a normal stable operation of the apparatus the contacts of switch 41 will be opened on the reverse movement of each stroke of the vibratory feeder or motor. normal negative grid bias on the tube 30 and permit current impulses to flow through the solenoid I5 which counteracts the action of spring 10 to maintain the amplitude of vibration of the deck I9 on armature shaft I3 substantially constant. Should there be any sudden increase in the amplitude of vibration of the deck I9 or armature shaft I3 this will not only break the contacts of switch 4'I' but will close the contacts of switch 41 for each stroke of the vibratory conveyor'or motor. When this condition is realized the positive bias on the grids of the tube 80 will increase substantially the flow of current to the solenoid 15 from the normal fiow, as above described, which will operate to reduce in a very short interval of time the current flow through the relays or valves 53, 54, 55. In other words,

This will remove the It is thus manifest that, ignoring for the moment the action of the control grids of the valves or relays I04-I09, inclusive, six phase pulsating current will be supplied from said valves or relays to the field winding I'I. As.is well known, such a current is a ;direct current with a very slight ripple which is of insignificant consequence.

To control the feeding of the current to the field winding I! in impulses as determined by the natural period of vibration of the vibratory conveyor or motor in the manner generally above described, the grids of the valves or relays I04I09, inclusive, are controlled from switch .mechanism 25 similar to the above described by obvious modifications which includes a six I- phase shifting mechanism similar to that seen at 04 in Fig. 2 and six grid control circuits with six control switches similar to the three grid control circuits and three grid control switches of Fig. 2.

The valves or relays I04-I09, inclusive, are of the type that in the absence of a positive grid bias, current will not fiow between the cathode and anode and, as is generally characteristic of these tubes, the amount of current fiow increases with an increase of positive grid bias.

With the deck l9 or armature shaft l3 out of engagement with the striking plate 39 the contacts of normally closed switch 45 will, of course, be closed and close the circuit from all of the cathodes by way of conductor I I to the negative terminal of grid biasing battery H2 across the terminals of which a potentiometer resistor H3 is connected. Adjustable contact H4 which cooperates with the resistor H3 is connected by way of conductor H5 to spring plate 51 and through the normally closed contacts of switch 45 to spring plate 42 which is connected by conductor H6 to all of the grids of the valves or relays Hi l-I09, inclusive, through. individual grid resistors, that for valve or relay I04 being seen at H1.

The phase adjusting mechanism 10 of Fig. 2 is employed intact as a grid biasing mechanism and the actuating rod 14 controls the position of the adjustable contact H4. The maximum stroke of the rod 14 is preferably sufiicient to cover substantially the entire resistor H3 from one terminal to the other.

As previously described, under normal conditions the spring 18 will move the plunger 13 to the extreme left which will make the grid bias on the grids of valves or relays I04|09, inclusive, a maximum in the positive sense. As a consequence, upon the closure of the main line switch (not shown), to the conductors I00, IOI and I02, six phase rectified, or resulting substantially steady current, will flow to the winding ll. of the motor 10 and attract the armature l4 thereof which, by virtue of the contact between the deck [9 or armature shaft l3 will interrupt this flow of current by breaking the contacts of switch 45 which remove the positive bias from the grids of the valves or relays lo l-I09, inclusive, which results in their becoming non-conducting, as above described.

This is effective to set the vibratory conveyor or motor into operation and the amplitude of vibration is maintained constant by virtue of the fact that the spring 18 tends to increase the current fiow in the winding I! to a maximum by providing a maximum positive bias on the grids, valves or relays I 04l09, inclusive, which will cause the closing of the contacts of switch 41 during the backward portion of each stroke of the vibratory motor in. Each closure of said contacts 4'! will cause .a momentary energization of the winding 75 by way of conductor I00, battery H2, conductor H8, solenoid l5 and conductor H9.

'Thiswill operate in a manner evident from the above description to urge the'solenoid 13 to the right, as viewed in Fig. 4, to decrease the current flow through the valves or relays l04-I09, inclusive, by reducing the value of the grid bias of each of said valves or relays.

As has been previously set forth, the mechanism for maintaining a substantially constant adjustable amplitude of vibration, as disclosed in Fig. 4 of the drawings, may be substituted for the mechanism for performing this function as shown the vacuum type, seen at I22, is interposed in the conductor I20. The grid of said valve or relay I22 is controlled through a grid resistor in the manner above described in connection with Fig. 4, it being understood that the conductors H0 and H6 of Fig. 5 lead to the same mechanism and circuit as the conductors H0 and H6 of Fig. 4.

From the above description of the invention it is to be noted that current of any frequency, and this expression includes direct current which has a frequency of zero, is controlled preferably by three electrode valves or relays, though any other well known type of controllable valves or relays may be employed, such as magnetrons, to deliver a pulsating current, the control means involving the interruption of a control circuit in which very small currents flow, if any. Furthermore, the frequency of the impulses are entirely independent of the frequency of the in-put current or the number of phases thereof so long as the delivered current may be of a substantially continuous character independent of the control grids.

Furthermore, the frequency of the delivered current is controlled directly by the mechanism to which the current impulses are delivered, which mechanism is designed to have a natural period of vibration which may or may-not be accurately predetermined and generally will not be predetermined with particular accuracy.

Still further, the amplitude of vibration of the vibratory conveyor or motor is automatically adjusted to be maintained substantially constant at any selected value which may be continuously varied between the maximum possible amplitude of vibration of the vibratory equipment and almost an imperceptible amount of vibration measurable in thousandths of an inch.

The apparatus and method has the distinct advantages of being operable from a source ofpower which may be of variable frequency; of not requiring exact tuning of the vibratory system to a predetermined frequency of vibration; and of providing for maximum efficiency of a vibratory conveyor or motor, which conveyor or motor acts directly upon the material or object to be treated, such as actingdirectly upon the conveyor pan which supports the material to be conveyed.

Furthermore, the automatic control of the amplitude of vibration acts as a protector for the vibratory conveyor or motor to prevent its doing damage to itself under no-load conditions.

Obviously those skilled in the art may make various changes in the details and arrangement of parts without departing from the spirit and scope of the invention as defined by the claims hereto appended, and I therefore wish not to be restricted to the precise construction herein disclosed.

Having thus described and shown an embodiment of my invention, what I desire to secure by Letters Patent of the United States is:

1. In a vibratory electro-magnetic apparatus, the combination with a deck, of a vibratory electro-magnetic motor comprising a main frame, a vibratory frame attached to said deck, spring means attaching said vibratory frame to said main frame for vibratory movement relative thereto and providing a vibratory system having a natural period of vibration, electro-magnetic means for deflecting and releasing said spring means periodically; an electrical system for controlling the flow of current to said electro-magnetic means comprising a power circuit having uni-directional gaseous electronic relay means in circuit with the electro-magnetic means, said power circuit and electronic relay means being so constructed and arranged that it is capable of delivering continuous current to said electro-ma netic means, and control means constructed and arranged to control periodically the flow of current through said electronic relay means thereby to vary the energization of said electro-magnetic means periodically from said power circuit, said control means including mechanism operated by said motor to control the periodic variations of current flowto said electro-magnetic means as determined by the natural period of vibration of said vibratory system, and including means for affecting said electronic relay means automatically to maintain substantially constant the amplitude of vibration of said deck at a predetermined amount.

2. In a vibratory electro-magnetic apparatus, the combination with a deck, of a vibratory electro-magnetic motor comprising a main frame, a vibratory frame attached to said deck, spring means attaching said vibratory frame to said main frame for vibratory movement relative thereto and providing a vibratory systenr having a natural period of vibration, electro-magnetic means for deflecting and releasing said spring means periodically; an electrical system for controlling the flow of current to said electro-ma'gnetic means comprising a power circuit having unidirectional electronic relay means in circuit with the electro-magnetic means, said power circuit and electronic relay means being so con- 'structed and arranged that it is capable of delivering continuous current to said electro-magnetic means, and control means constructed and arranged to control periodically the flow of current through said electronic relay means thereby to'energize said electro-magnetic means periodically from said power circuit, said control means including mechanism operated by said motor to control the periodic flow of current to said electro-magnetic means as determined by the natural period of vibration of said vibratory system, and including means for varying the amplitude of vibration of said deck.

3. In an electrical system, the combination with a vibratory apparatus including a deck and an.

electro-magnetic motor forming a vibratory system having a natural period of vibration, of a source of electrical current of any'availabl frequency, and means including gaseous electronic relay means so constructed and arranged that it is capable of delivering a continuous current to said electro-magnetic motor controlled by the vibratory movement of said motor and constructed and arranged to cause electrical impulses to be delivered from said source of current to said motor to vibrate said .vibratory system at its natural period of vibration, and further including means operative automatically to maintain the amplitude of vibration of said deck substantially constant at a selected value.

4. In an electrical system, the combination with a vibratory motor including a vibratory system having a natural period of vibration, of a source of electrical current, means, including gaseous electronic relay means for conducting and controlling a flow of current from said source to said motor, said means being so constructed and arranged that it is capable of delivering continuous currenttosaid motor means for controlling the flow of current through said relay means to cause it to flow in impulses including control circuit means,

means operated in response to the frequency of the vibratory movement of said motor for controlling said control circuit means to control the frequency of the current delivered to said motor to maintain the frequency of said impulses in synchronism with the natural period of vibration of said vibratory system, and amplitude responthe amplitude of vibration of said motor to urge said controller toa current decreasing position upon a predetermined amplitude of vibration. being reached.

. 6. In an electrical system, the combination with a vibratory electromagnetic motor, of a source of alternating current, a plurality of three electrode electron relays for controlling a flow of pulsating current from said source to said motor, a grid control circuit individual to each relay,

means for controlling said grid control circuits to render said relays successively conducting and non-conducting at a frequency determined and controlled by said motor, and means including phase adjusting mechanism for supplying undulatory potentials to said grid circuits and controlled by the amplitude of vibration of said motor to maintain its amplitude substantially constant.

7. In an electrical system, the combination with a vibratory motor including a vibratory system 4 having a natural period of vibration, of a power circuit for said motor including gaseous electronic relay means for conducting and controlling a flow of current from a source to said, motor and being so constructed and arranged that it is capable of delivering continuous current thereto, means for controlling the flow of current through said relay means, means responsive to the frequency of vibration of said motor as determined by the natural period of vibration of said motor for controlling said control means to cause current impulses to now to said motor at a frequency in synchronism with said natural period of vibration, and means responsive to the. amplitude of vibration of said motor supplementary to said frequency responsive means constructed and arranged to exercise a further control on .said control means to maintain the amplitude of vibration of said motor substantially constant, said last named means including means for varying a voltage applied to said controlmeans.

8.'In an electrical system, the combination with a vibratory motor including a vibratory system having a natural period of vibration, of a power circuit for said motor including gaseous electronic relay means for conducting and controlling a flow of current from a source to said motor and being so constructed" and arranged that it is capable of delivering continuous current thereto, means for controlling the flow of current through said relay means, means responsive to the frequency of vibration of said motor as determined by the natural period of trol means to cause current impulses to flow to said motor at a frequency in synchronism with said natural period of vibration, and means responsive to the amplitude of vibration of said motor supplementary to said. frequency responsive means constructed and arranged to exercise a further control on said control means to maintain the amplitude of vibration of said motor substantially constant.

9. In an electrical system, the combination with a vibratory motor having a load supporting deck and including a vibratory system having a natural period of vibration, of a source of alternating current, a power circuit for said motor including electronic relay means having an anode and a cathode for conducting and controlling a flow of current from said source to said motor and being so constructed and arranged that it is capable of delivering continuous current thereto, a control circuit energized from a source of I alternating current including means for controlling the flow of current through said relay means comprising grid means therefor, means responsive to the frequency of vibration of said motor as determined by its natural period of vibration for controlling said control means to cause current impulses"to flow to said motor at a frequency in synchronism with said natural period of vibration, and means responsive'to the amplitude of vibration of said motor supplementary to said frequency responsive means constructed and arranged to exercise a further control on said control means to maintain the amplitude of vibration of said motor substantially constant by automatically adjusting the phase relation between the anode and grid voltages of said relay means.

source of alternating current, a power circuit for said motor including electronic relay means having an anode and a cathode for conducting and controlling a flow of current from said source to said motor and being so constructed and arranged that it is capable of delivering continuous 10. In an electrical system, the combination 4 with a vibratory motor having a load supporting deck and including a vibratory system having a natural period of vibration, of a source of alternating current, a power circuit for said motor including electronic relay means having an anode and a cathode for conducting and controlling a flow of current from said source to said motor and being so constructed and arranged that it is capable of delivering continuous current thereto, a control circuit energized from a source of alternating current including means for controlling the flow of current through said relay means, means responsive to the frequency of vibration of said motor as determined by its natural period of vibration for controlling said control means to cause current impulses to flow to said motor at a frequency in synchronism with said natural period of vibration, and means responsive to the amplitude of vibration of said motor supplementary to said frequency responsive means constructed and arranged to exercise a further control on said control means to maintain the amplitude of vibration of said motor substantially constant by automatically adjusting the phase relation between the anode and control means voltages of said relay means.

11. In an electrical system, the combination with a vibratory motor including a vibratory system having a natural period 01' vibration, of a current thereto, a control circuit energized from a source of alternating current including means at a frequency in synchronism with said natural period of vibration, and means responsive to the amplitude of vibration of said motor supplementary to said frequency responsive means constructed and arranged to exercise a further control on said control means to maintain the amplitude of vibration of said motor substantially constant by automatically adjusting the phase relation between the anode and grid voltages 01 said relay means.

12. In an electrical system, the combination with a vibratory motor including a vibratory system having a natural period of vibration, of a source of alternating current, a power circuit for said motor including electronic relay means having an anode and a cathode for conducting and controlling a flow of current from said source to said motor and being so constructed and arranged that it is capable of delivering continu ous current thereto, a control circuit energized from a source of alternating current including.

means for controlling the flow of current through said relay means, means responsive to the frequency of vibration of said motor as determined by its natural period of vibration for controlling said control means to cause current impulses to flow to said motor at a frequency in synchronism with said natural period of vibration, and means responsive to the amplitude of vibration of said motor supplementaryto said frequency responsive means constructed and arranged to exercise a further control on said control means to maintain the amplitude of vibration of said motor substantially constant by automatically adjusting the phase relation between the anode and control means voltages of saidrelay means.

13. In an electrical system, the combination with a vibratory electro-magnetic motor, 01' a source of alternating current, electronic relay means having at leastthree electrodes including a grid and connected to control aflow of pulsatory current from said source to said motor, a grid control circuit, means for controlling, said grid control circuit to render said relay successively conducting and non-conducting at a frequency determined and controlled by said motor, and means including phase adjusting mechanism for supplying undulatory potentials to said grid control circuit and controlled by the amplitude of vibration of said motor to maintain said amplitude substantially constant.

HARKER H-\ HITTSON. 

